Polymerization of hydrocarbons



May 13, 1947. w. B. sHANLr-:Y

POLYMERIZATION OF HYDROCARBONS Filed March 26, 1942 Nw Y h tilllnvm,

atented May 13, 1947 William B.

Universal Oil Products Company,

Shanley, Chicago, Ill., assigner to Chicago, Illl,

a corporation of Delaware Application March 26, 1942, Serial No.V436,310 6 Claims. (Cl. 26o-683.15)

This is a continuation-in-part of my copending application Serial No.339,268, filed June '7, i940,

This invention relates to a process for eiecting the polymerization ofnormally gaseous olefin hydrocarbons into liquid olens utilizabledirectly as high antiknock constituents of motor fuel or afterhydrogenation as components of motor fuels which are required to be of asubstantially saturated character such as aviation fuel.

In a more specic sense the invention is concerned with improvements incatalytic polymerizing processes operated in conjunction with petroleumcracking plants to recover motor fuel values from the gases producedincidental to cracking.

Polymerization of olefin-containing gases is carried out at the presenttime commercially by both thermal and catalytic methods, the formeroperating at relatively high temperatures and pressures and givingsubstantial yields vof aromatics as well as olens and the latteroperating at distinctly lower temperatures and frequently lowerpressures to produce a definitely olenic product. In the catalyticprocesses a type of catalyst which has met with commercial success isthe so-called solid phosphoric acid catalyst as described in UnitedStates Patent No. 1,993,513 and others. In this process olefincontaininghydrocarbon gas mixtures are passed through stationary beds of granularmaterial consisting essentially of prepared particles made byincorporating a phosphoric acid with a relatively inert and generallysiliceous material to produce a paste which is either calcined toproduce a cake which is ground and sized to recover the catalystparticles or extruded to produce particles which are later calcined. Ineither case the prepared particles are subjected to a controlledsteaming operation to iix the proper composition of the activepolymerizing acid in respect to its degree of hydration.

In commercial plants'it is customary to operate with a number ofpolymerizing chambers iilled with this type of catalyst and it is morecustomary practice to operate with catalyst towers in series since thecatalyst becomes spent after a period of use and needs reactivating orreplacing, and since the reaction of polymerization is exothermic andcooling is frequently required between the reactors in a series toprevent an undue rise in temperature which may result inover-polymerization with the formation oi undesirably high yields ofpolymers boiling above the gasoline range. Obviously there will be aconsiderable pressure drop along the line of flow through the series ofcatalyst towers which introduces another factor which must be consideredin a successful operation of such a cated in more detail `by referenceto the attached 2 plant to produce optimum yields of desired products.vThe present' process isfan improvement in processes forpolymerizing-normally gaseous olefin hydrocarbons toorm' liquid polymerstherefrom while utilizing solid granular catalysts; particularly thesolid phosphoric acid catalysts briefly describedl above, although theimproved process will find ready application to all similar processes ofan exothermic character.

In one specific embodiment. the present process consists in preheati'nga portion of olencontaining hydrocarbon gases to a temperature abovethat necessary for :eicient polymerization of the olens in the gasmixture on `passing through polymerizng-'catalysts, and passing thepreheated material in-A parallel through separate beds of polymerizingcatalyst after reducing the temperature of the individual streams ofgases by the injection of controlled amounts of unheated charge so thatthe temperature of the charge entering each reactor. is optimum `for theproduction of liquid polymers in each reactor; the variedtemizieraturr-:sv being required to compensate for catalysts ofdifferent degrees of activity. f f

The character of thepresent process is indidrawing which showsdiagrammatically in general side elevation an arrangement ofinterconnected elements in which operations falling within the scope ofythe invention may be carried out. The drawingis not to scale and doesnot purport to contain all? of the details of apparatus which may befound'in commercial plants.

Referring to the drawing a charging stock which may convenientlybe aso-called propanebutane fraction from the stabilizer of a cracking plantmay be introducedunder pressure through line I containing valves 2 and 3while a portion ofthe charge is passed through a heating element 4disposed to receive heat from a furnace 5 wherein it is heatedv to atemperature higher than that required for` best operation of theparallel beds of catalyst following. As a rule temperatures of over 500F.' are not used in the polymerization of such 'gas mixtures with solidphosphoric acid catalyst andthe charge will not ordinarily be heatedabovek this approximate point. With a very active catalyst, eitherfreshly prepared or freshly reactivated,- temperatures as low as Z-300F. maybe employed when it is desired, for example, to selectivelypolymerizethe more reactive oleflns such as isobutene to produce specialproducts.

The heated products from heating element l pass through line'6containing valve 1 after thek tive life of the catalyst since morehighly dehydrated acids than Dyrophosphoric acid have a decreasing`catalytic activity. The heated materials pass to a header I abovereactors. I3, I9, 24, and 28 arranged in parallel, lines II 'containingvalve I2, I1 containing valve I8, 22 con-` taining valve 23, and Valve21 Avat the, end of header I0 permitting the introduction of the premerbeing withdrawn through line 4I containheated charge into thepolymerizersin the-order` named.

In accordance with the present invention-ja. portion of theolefin-containing gas mixture bypasses heating element 4 vand goesthrough line 45 containing valve 46 to aheader 4l whichhas branchconnections leading either into the Vtop ofthe reactors or to points inthe reactor intermediate in` the line of V flow of the reactants. Thusline 48 containing .valve 4'9 leads from header 41,-into the heated gasmixtures entering reactor I3 while another branch line 48' containing avalve 49., leads to an intermediate lpoint in the reactor. Similarly1ine.,50 containing valvev5i leads directly to the top of reactor` I8while branch line SU'cOntaining valve 5I leads to a .middle pointthereof. -In the case of reactor 24 branch` line 52 `containing valve 53leads unheated quenchingv gases intol thegtop of reactorv 424 whilebranchline 52'.rcontaining valve/,53'

leads to an intermediate point. Lastly as shown in the drawing, the useof valve 54 permitsv the introduction of unheated quenching gases intothe top of, reactor 28 while abranch line 54! containing valve 5' leadsto an intermediate point inthe reactor. 1 2 Y. Y It will -be obviousthat by the manipulation `of the valves in the branchlines `from header41 that the preheated charge from `header I0 may `be reduced in.temperature to any desired point i which correspondsA to optimumoperation in the respective polymerizing zones. The temperatures usediinany one reactor -will depend upon the 'activityA of the catalyst whichin turn depends upon whether it is` fresh orA reactivated or partlyspent and the degree of conversion desired in `this particular reactor.`It will-be obvious that .not only maydifferent types of polymerizationbe conducted in individual reactors by means of the present process butthat in general the'overall pressure drop through the plant will begreatly reduced so that the operation is more exactly controlled and theplant is therefore more'exible. It is also obviouslyl possible tooperate different reactors under different conditions of temperature sothat one may become spent ahead of the othersgand provide a basis forrotating the towersas the catalyst which they contain becomessuccessively spent at Whichtime they may be cut out'of the line of flowand either reactivated in situ by oxidizing off carbonaceous `depositsand later steaming or finally disposed of as the economics ofthe processmay warrant. Lines I4containing valve I5, 20 containing valve 2|, 25containing valve 26 and 29 containing valve 3U permit the withdrawal ofreaction products from the polymerizers I3, I9, 24, and 28 respectivelyinto header I Swhich contains Aa valve 3| and whichI leads to afractionator 32, which is intended to represent any type offractionating equipment which may be used to separate unreacted gasesfrom the polymer product and permit the production of aV polymerfraction of desired Vboiling range. As shown in the drawing.fractionator 32 has a Vlower draw line 33 containing a valve4 34 whichpermits the withdrawal i of polymer material heavier than that desiredin ing valve 42 and the latter through line 43 containing valve 44.Although not indicated in the drawing the gases separated from receiver40 may be recycled to further treatment to effect further polymerizationof any oleflns which may have escaped reaction from the first passagethrough the catalyst bed.

It will be seen from the preceding description o! the invention that theprocess thereof can be operated in a variety of ways upon differentcharging stocks to produce a variety of products sc that it is notpossible to completely indicate the commercial possibilities of th'eprocess by a single example. However, the succeeding data isillustrative although it is not introduced with the intention of undulylimiting the proper scope of the invention.

A plant of the general character described in connection with thedrawing is utilized to polymerize a butane-propane fraction whichcontains about by volume of so-called higher olens, including propaneand butenes, the remainder of the constituents being principally propaneand butanes. The ch'arge is preheated to a temperature vof 405 F. andpassed in parallel .through three reactors containing solid phosphoricacid catalyst, the fourth in the series being in the reactivation cycle.The three reactors contain catalyst of varying activity. The rst reactorcontains a catalyst from a second previous reactivation and is oi'moderate to low activity. The second reactor contains a catalystreactivated after an immediately preceding cycle and is somewhat moreactive than the catalyst in the first reactor. The third reactorcontains freshly reactivated catalyst which has a relatively highactivity comparable with freshly prepared catalyst. Cooling ofthe inletstream to the second of the three reactors is done by introducinganunheated charge at the inlet of the f reactors while cooling-of th'ethird'reactor is done by` introducing controlled amounts of the unheatedcharge at both the inlet and a central Vpoint in the reactor since therewill be a tendency for the greatest temperature increase to occur inthis reactor containing the most active catalyst. For the gas mixturetreated it is found -that the best results in overall yields areobtained while the average temperature throughout eachl reactor is 435F. -The following tabulation shows the inlet and the exit temperature'of the three reactors during the first period of a run:

' It will be observed that by the combination of preheating andquenching at the entrance to the second reactor and at both the entranceand at the middle pointof the third reactor containing freshlyreactivated catalyst that all `three reactors aregheld at an averagetemperature which produces maximum olen conversion and that this resultis obtained without exceeding 475 F. which is regarded as the maximumuseful outlet temperature. If preheating and quenching are .notemployed, the proper average temperature will only be obtained onreactor I with reactor 2 operating above the desiredaverage and reactor3 operating above the desired average with an outlet temperature wellabove the desired useful maximum.

There is produced by this type of operation over the period stated sevengallons of polymer material per 1000 cu. it. of inlet gas, the mixedpolymers having an octane number o! 82 by the motor method. The ultimateproduction per pound of catalyst is 60 gallons.

I claim as my invention:

1. A process for producing polymers from a normally gaseous oleflniccharging stock which comprises passing an olefinic gas stream through abed of relatively active polymerizing catalyst, simultaneously passing asecond stream of olenic gas through a bed of less active polymerizingcatalyst, heating a portion of said charging stock to a temperaturesuitable for effecting polymerization in the second-mentioned bed andsupplying separate portions of the heated gas to said beds, andcommingling an unheated portion of said charging stock with the heatedgas being sup-v plied the inst-mentioned catalyst fed in sufficientamount to maintain in the more active catalyst bed an averagepolymerizing temperature substantially uniform with the averagepolymerizing temperature prevailing in the less active catalyst bed.

2. A process for producing polymers from a normally gaseous oleniccharging stock which comprises passing an olenic gas stream through abed of fresh solid phosphoric acid catalyst, simultaneously passing asecond stream of olefinic gas through a bed of partially spent solidphosphoric acid catalyst, heating a portion of said charging stock to atemperature suitable for effecting polymerization in thesecond-mentioned bed and supplying separate portions of the heated gasto said beds, and commingling an unheated portion of said charging stockwith the heated gas being supplied to the first-mentioned cataiyst bedin sufncient amount to maintain ni the more active catalyst bed anaverage polymerizing temperature substantially uniform with the averagepolymerizing temperature prevailing in the less active catalyst bed.

3. A process for producing polymers from a normally gaseous olefiniccharging stock which comprises maintaining under polymerizing conditionsa rst bed of` relatively active polymerizing catalyst and a second bedof less active polymerizing catalyst, heating a portion of said chargingstock to a temperature suitable for eiecting olefin polymerization insaid second bed and supplying separate portions of the heated gas tosaid beds, and introducing t0 said first bed an un- 6 heated portion ofsaid charging stock in sulcient amount to maintain in the first bed anaverage polymerization temperature substantially uniform with thatprevailing in the second bed.

4. The, process as dened in claim 3 further characterized in that atleast a portion of said unheated charging stock is commingled with theheated gas being supplied to said first bed.

5. The process as dened in claim 3 further characterized in that atleast a portion of said unheated charging stock is introduced at anintermediate point of said ilrst bed.

6. A process for producing polymers from a nor- I mally gaseous olefiniccharging stock which comprises maintaining under polymerizing conditionsa first, a second and a third bed of polymerizing catalyst, lyticactivity in the order named, heating a. portion of the charging stock toa temperature suitable for effecting olefin polymerization in said thirdbed of lowest catalytic activity, supplying separate portions of theheated gas to said beds. commingling unheated portions ofthe chargingstock with the heated gas being supplied tothe first and second beds,and introducing a further unheated portion of the charging stock at anintermediate point of said first bed of highest catalytic activity, theamount of unheated charging stock thus supplied to the nrst and secondbeds being sufficient to maintain in each of these beds an averagepolymerizing temperature substantially uniform with that prevailing insaid third bed.

WILLIAMB. SHANLEY.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,222,304 Simpson et al Nov. 19,1940 2,165,631 Gerhold July 11, 1939 2,154,795 Westenberg Apr. 18, 19392,040,658 Kuentzel et al. May 12, 1936 2,186,275 Story Jan. 9, 19402,096,204 Seguy Oct. 19, 1937 2,198,545 Levine Apr. 23,' 1940 V2,245,735Subkow June 17, 1941 '2,266,095 Thayer Dec. 16, 1941 2,198,180 RubinApr. 23, 1940 2,268,618 Pyzel Jan. 6, 1942 2,242,627 Strickland May 20,1941 2,170,275 Nelson Aug. 22, 1939 2,373,888 Hachmath Jan. 30, 19452,368,110 Buell Jan. 30, 1945 FOREIGN PATENTS Number Country Date451,788 Great Britain Aug. 12, 1936 456,637 Great Britain Nov. 12, 1936said beds b eing of decreasing cata-

